Switch



w. c. zAUG March 2, 1954 SWITCH Filed May l5, 1951 INVENTOR.

WILL-IAM C. ZAUG Patented Mar. 2, 1954 SWITCH William C. Zaug, Huntington, N.

Corporation, corporation of New York Telephonics Y., assignor to Huntington, N. Y., a.

Application May 15, 1951, Serial No. 226,495

1 Claim.

This invention relates to switches, and has particular reference to the push button type of Switch used in telephonie the invention is not limited to that use.

Inv military eld communication, it is desirable that at least part cf the equipment, particularly the microphone, be disconnected except during use, and it has accordingly become the practice to provide a thumb or other finger switch button which may be conveniently pressed when talking, and released when listening, so that power is conserved and the transmission circuits do not remain closed when not in use. Such switches must be operative at all times, and must be generaly immune to deterioration -by reason of dampness, fouling or other results of rigorous usage in the eld.

In a preferred embodiment of the invention, a spring-held plunger in the form of a thumb or finger button is arranged to be pressed to shift connections from one circuit to another and each circuit is a dual circuit, so that closure of the circuit even in the case of impairment of one set of contacts thereof is insured. 'I'he contacts are preferably of the wiping kind, so that they are self-cleaning and the uniform wiping pressure between them is not affected after almost innumerable actuations of the switch. c

More specifically, the plunger operated by or including the thumb or finger button is slidably mounted in an insulating block and normally urged to one position by a spring initially presenting maximum resistance to downward movement and decreasing such resistance on continued movement of the plunger. The plunger carries contact plates on opposite sides of a length to bridge at one time two of three spring wiper contacts arranged parallel to the surface of the corresponding contact plates and so spaced that 'when theplunger is forced from one extreme position to the other, the center wiping contact and one or the other of the remaining contacts are simultaneously in engagement with the plunger contact plate. The wiper contact may be divided in two sets for controlling two or more circuits, and to that end they are duplicated on the opposite side of the switch block so that if the operation of one set becomes impaired, the circuit closing function of the other set is maintained.

It will be seen that the switch of' this invention affords a very simple, compact and reliable arrangement for performing its intended functions under the most adverse conditions of field operation.

For a more complete understanding of the invention, reference may be had to the accompanying drawings, in which:

Figure 1 is an elevation of the switch of this equipment, although (Cl. 20G-16) invention with a portion of the switch block and plunger broken away to show their construction;

Fig. 2 is a transverse section through the switch as seen along the line 2 2 of Fig. 1; and

Fig. 3 is a plan view of the switch with a portion thereof broken away to show the construction of' the switch block.

Referring to the drawings, numeral I0 designates the switch block and numeral I I the plunger, whose free end I2 constitutes the finger or thumb button, which projects from the appara` tus at a convenient place for engagement by the thumb or finger of the operator with the remainder of the switch enclosed within the casing of the instrument in the usual manner.

As shown particularly in Fig. 3, the switch block I Il consists of a pair of plates I3 of suitable insulating material, such as. a phenolic resin, cemented or otherwise secured together by a layer of cement I4 or other material for uniting the two plates I3 into the unitary block IIJ.

Secured to each plate I3 by a rivet I5 is a wiping contact 20 comprising a cooperating pair of opposed spring fingers I6 .and I'I. Wiping contact 20 is preferably formed by folding a strip of spring sheet metal upon itself with the folded end I8 thereof serving as the soldering lug for connecting wires. The free ends of the folded strip form the fingers I6 and I 'l which are spaced apart a distance slightly less than the thickness of the contact plate I9 whose opposite surfaces are adapted to engage as shown in Fig. 3.

One half of the switch block I6 comprising the plate I3 is provided at one lateral edge with three contacts 20 spaced apart as shown in Fig. 1. The opposite lateral edge of plate I3 is provided with three similarly spaced wiping contacts 20 whose spring fingers I6' .and Il are adapted to resiliently engage the opposite surfaces of contact plate 2I in the same way that spring ngers I6 and Il of wiping contacts 20 engage opposite surfaces of contact plate I9.

As shown particularly in Fig. 1, contact plates I9 and 2I are carried by a strip 22 of suitable insulating material such as a phenolic resin, which slides in a vertical groove 23 formed in the outer surface of plate I3. The free end of strip 22 extends beyond plate I3 to form the finger or thumb button I2 along with the complementary strip 22 sliding vertically in a slot 23 in the outer surface of plate I3 and riveted together by rivets 24 and 25, the latter passing s through an elongated slot 25 passing through plates I3 and I3. prise plunger II.

It will be observed from Fig. l that Contact plates I9 and ZI are riveted to strip 22 of plunger II and are spaced apart so as to be electrically separate. The width of contact plates I9 and 2| 'I'he strips 22 'and 22 comshown particularlyin Figs. 1 and 2.

in the direction of movement of the plunger II is such as to bridge two each of the wiping contacts 20 and 20 at any one time. Thus in the outward position of the thumb or finger button I2, switch plate I9 is simultaneously bridged by the upper and center wiping contacts 2B and when in the depressed position of thumb or finger buttonV I2, the switch plate I9 is disengaged from the upper wiping contact 20 and bridges only the center and lower wiping contact 20 as shown in dotted lines in Fig. l. Similarly, switch plate ZI bridges upper and center wiping contact 20 when the finger or thumb button I2 is in the upper or outer position, and when the latter is depressed to the dotted line position in Fig. 1, switch plate l 2l is disengaged from the upper wiping contact 20 and bridges the center and lower wiping contants 28".

The opposite side of the switchA of this. invenf tion is constructed identically to` the side just described, switch plate I3 carrying wiping con,- tact 20." on` one edge, which is insulated from wiping contact Zl" along the opposite edge of plate I3. Wiping contact 20 and cooperating contact plate I3 correspond in every waywith wiping contacts 2i! and contact plate I9, whereas wiping contacts 28" and cooperating contact plate 2l' correspondA in `every way with wiping contact 2D. andV contact plate 2i, respectively. Accordingly, the opposite faces of the switch are identical, but insulated from each other.

The normal conditionwof the switch is illus trated in Figs. l and 2, wherein the contact plates I9, IS', 2| and2 I' bridge the corresponding upper and center wiping contacts 20, 201 20 and 2li The respective wiping contacts are urged to. this normal position by a spring 2 which lies within the inverted U.shaped plunger II .composed of the finger or thumb button I2 and plates 22 and 22. 'Spring 21 extends to either side of plunger II to rest at its free ends on abutments 28 seated in suitable recesses in the switch block II]` as Spring 21 is shapedL with an outwardlysdirected center hump engaging the lower surface of the thumb or nger button i2 and has concave portions at either side of the central hump.

A spring 21 so shaped has the characteristic of presenting a maximum resistance to the dow-nwardr or inward movement of the thumb o r finger button I2 upon initial movement thereof and decreasingl such resistance on continued movement of button I2, so as to afford an initial resistance tothe pressure of the thumb or finger-- and to restoreV the button I2 rapidly and positively when the pressure thereon is released. VThe dotted lines in Fig. 1 show the spring 21 in its flattened, tensioned position when button l2 is pressed inwardly to the limit of movement which isdetermined in both directions by thel length of slot 21,6. Thus, rivet 215 engages the upper end of slot 26 tolimit the outward movement of plunger IIb by spring 21. and engages the lower end of slot 2S to lim-it: the inward movementA of plunger II.

Inoperation of the switch of thisv invention such asv on a hand telephone of the so-calied walkie-talkie type, the normal or outward position of button I2l holds the contact plates I9'l and 2I in the open or listening circuit position, for example, andthe depressed position of contact plates I9 and 2-I closes the talking circuit, forl example. rlhe opposite contact plates I 9 and 2|" with the corresponding wiping contact 20j' and 20' duplicate the aforementioned circuits if desired, and may be used to preclude interruption of one or both of the circuits closed by contact plates I9 and 2I, or vice Versa.

The wiping pressure afforded by the spring fingers ISand Il of the wiping contacts 20 maintains good and clean contact, since the pressure thereof on corresponding switch plate I9 does not vary, and is not changed by exing of the contact fingers IE and II, since the thickness of the contact plate I9 is uniform and its movement is always parallel tothe contacting surfaces of the spring fingers IB and I1. The same operating conditions obtain for the spring contact fingers of wiping contactsZ', 20" and 20' with respect to contact plates 2I, IS and 2 I respectively.

.It will be understood that the leads to the telephone and other circuits controlled by the switch of' this invention will be soldered to the lugs I8 .of the wiping contacts 20. and' thecorresponding sil'dering lugs of wiping contacts 2n', 2c," and 2 PII.

Although a preferred embodiment of the inventinav has been, illustrated and described here it is to be understood thatthe. invention is not limited, thereby, but is susceptible of changes in form, and detail within the scope of the appended Gleim.

I claim:

in. a switch fortelephonic apparatus andthe like, the combination of an insulating block oomprising a pairof mated plate sections having an elongated recess formed at one edge, abutment means at opposite ends of said recess, a'row ci spaced contact elements mounted en one surface of said block with their contact points lying `Vin a common plane, a plunger mounted on said-block l for movement parallel to :saidl row of contact elements, said plunger comprising a pair of spacedf apart Sido portions movable near the respective sides of said block and embracing saidrecess, and o heodportion joining. said side portions. andl over- 1 lying saidroooss., @contact plate mountedoo said plunger and having its contact.surfaoemovable in said plane for wimpels engaging, the contact points of said oootaoteiements upon actuation of seid plunger, a Second row of spaced contact ele# monts. mounted the opposite Surface of said block. parallel to the direct' n ofV movement. oi ,Said plunger with their contact points lions a scoorilv common plane parallel tosad first plane second. Contact plato mounted on said; plunger and: having its contact. surface movable Said second plane for wipinely engaemetho Contact no.. le Oisaidsooono contact elements ation of said` plunges and. e loaf spring: inter posed between said blocken@ Seid plum er for ref stof e the Same to. predator.: ined positionering re, .Y off-actuating pressure ,oreon, said spring be e; soateei seidreoess its. ends being adapted: to engage said abutment means, said illlg: haring/a; Qcntralhump portion for-reacting asainsttho head; portion of said plunger and: a. hair Off concaye portions ateither side of: said central; hump nutrirsi/iv o. asno..

Eef.orences4 Cited. the file of this patent UNITED STATES PATENTS 

